A friend has offered to pay me to manage a house he owns in the Greater Hartford area. 

I lost contact with the lady living there but her boyfriend, that I have only met once (he is on the lease but never lived in the house) tells me her ex-boyfriend was creating problems so she moved out and is not able to talk...

Outside of getting a partner to help, I really don't have any creative solutions for you that won't leave you in the poor house at the end of the day. 

I've recently came across this technique of assuming the sellers mortgage when purchasing the house.

With an increasing demand for affordable housing options and steady population growth in the area, small multi-family properties are becoming attractive investment opportunities for investors looking to diversify their portfolios.Spokane offers a unique blend of urban amenities and outdoor recreational opportunities, making it an appealing location for tenants and potential property buyers alike.

I recently purchased a property that includes a 3-bedroom, 3-bathroom main house and a pool house that can be converted into a 2-bedroom, 1-bathroom unit.

Tickling ears just isn't in my wheel house.

I have a house there and we've cycled through a few different ones. 

I would not charge install fee.I have one rental property for about half a year no  so I haven't had to deal with any move out procedures or getting a place "rent ready" since my house hack is a new build but how did you create your "move out instructions" and are you supposed to paint the whole inside every time a tenant moves out? 

If you're paying on time they don't care if Santa Claus owns the house."